Freud described the human personality as being divided in three major parts.
These are:

• The id
  The part of personality containing the libido
  The basic part of personality and is present at birth
  Basically operates on the pleasure principle
• The ego
  The part of the personality that helps the person have realistic, rational interactions
  Operates on the reality principle and tries to keep the id in line
• The superego
  The part of the personality containing the conscience
  Contains the values and ideals of the society that we learn
  Operates on idealism
  Its aim is to inhibit the impulses of the id and to persuade the ego to strive for moral goals rather than realistic ones